The thermal protectant category is relatively new and has grown out of a need to protect hair from the damaging effects of blow dryers, flat irons and curling irons. Applying heat is an easy and convenient way to set hair in a desired configuration, but doing so has detrimental effects, namely heat damage.
Hair is composed of an inner medulla surrounded by a cortex layer that is protected by several cuticle layers. Cuticles are like shingles on a roof that protect hair from the elements. When repeatedly exposed to heat, they gradually degrade, exposing the cortex layer. Such damage is difficult to repair and often leads to hair that has split ends or gets unmanageable in hot, humid weather, causing it to become frizzy. Rather than try to make repairs at this point, it is best to take preventative measures before such irreversible damage occurs.
Thermal protectants are products that are applied to hair before it is exposed to heat. They act as a barrier, preventing the heating elements from directly touching the bare surfaces of the cuticle layers. Products that are effective form a nice uniform layer that can deflect heat. They also help create and maintain the desired style, even in hot humid environments.
The product composition is usually a polymer or mixture of polymers along with a combing aid, such as silicone (EU) or vegetable oil (EU). Polymers used should have a low glass transition temperature so that they can flow easily when heat is applied. They can be dispensed in a convenient spray form or can also be applied from a foaming product such as a hair mousse. After application, hair is combed to ensure that there is a uniform, thin protective layer. Hair is then styled with any heat appliance such as a blow dryer or flat iron to give the desired style. Other desirable properties of thermal protectants are easy removal with a conventional shampoo and a pleasant feel.
To determine if the products are effective, hair fibers are examined under a scanning electron microscope, where the hair surface is magnified 5,000 times. Such magnified images show the extent of hair damage or lack of damage to the cuticle and other surfaces of the hair. Images of treated and untreated hair are compared side by side to determine if hair has been protected from the heat of the styling appliances.
To learn more about these and other test methods, please contact Bria Research Labs.
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